[UniPol]

I recall a few years back having a PST and SM40 . The SM40 etalon screwed directly onto the PST hence a double stacked arrangement. The problem I found was that there were double images, ghosting and flaring owing to the fact that the two units are tuned separately so that a fair bit of fiddling was necessary to tune the image. The final image was much darker however surface features were evident but prominences were almost lost.

Perhaps somebody may correct me but I thought double stacked scopes units were supposed to be tuned at the factory? at least pre Meade Coronado's said this in their advertising some years ago. I get the impression that anybody who buys a dedicated double stacked set up don't appear to have any issues.